Some frequency-modulated circuits have a steep transfer curve of output power vs. input frequency. A small frequency change in the input signal may result in a large output change, and therefore, accurate control of the input signal frequency may be desirable. In some examples, generating input signals by counting whole clock cycles of a system clock may not yield a resolution fine enough to accurately control the input signal frequency. Some techniques to increase resolution may also increase system power consumption or increase system complexity and cost.